Eight-time champion Rafael Nadal also had little trouble reaching the last eight, beating Andreas Seppi 6-1 6-3, while Roger Federer shook off a slow start in a 6-4 6-1 win against Lukas Rosol.

Second seed Djokovic had won his second-round match in 45 minutes and has not been tested this week, while the top seed Nadal has looked a bit sloppy at times.

Djokovic took only 22 minutes to win the first set, sealing it with a crisp forehand that glided past Carreno Busta. His Spanish opponent then received loud cheers, clenched his fists and grinned broadly when he won his first game to pull back to 3-1 in the second. Djokovic served out the match, tormenting him one last time with an exquisite drop shot.

Having looked a little rusty in the second round, where he trailed 3-1 against Teymuraz Gabashvili, Nadal was more clinical and raced into a 4-0 lead.

"I think today I played a little bit better than yesterday," said Nadal, who lost last year's final to Djokovic. "I was playing at a good level, changing the directions very well, playing with the right intensity."

He next faces sixth-seeded David Ferrer, who easily beat Grigor Dimitrov 6-4 6-2, while Federer will face Jo-Wilfried Tsonga, and Djokovic takes on Guillermo Garcia-Lopez after his shock 4-6 6-3 6-1 win over Tomas Berdych.

Nadal has a 21-5 career record against Ferrer, winning 10 of the past 11 meetings since Ferrer beat him in straight sets at the Australian Open in 2011 - the year he also lost to Nadal in the Monte Carlo final.

"David is a tough, tough player on any surface," Nadal said. "But here on clay, always a big challenge."

Rosol, meanwhile, broke Federer in the third game and held for a 3-1 lead.

"It was a bit rocky in the beginning," Federer said. "I thought Rosol was going to play much more aggressive early on. I was expecting the rallies to be shorter. When they extended, I made too many mistakes."

But Federer broke back with a stinging cross-court forehand that landed at Rosol's feet, and then broke him to love - clinching the set when Rosol's forehand sailed long.

Federer has a 10-4 record against Tsonga, who beat him in the French Open quarter-finals last year and in the Wimbledon quarters in 2011.

"I've seen Jo play different kind of quality matches lately, so not quite sure he's going to play, how aggressive, how passive," Federer said. "I'm going to have to have an open mind."

Australian Open champion Stanislas Wawrinka and Milos Raonic of Canada also advanced.

Having taken only 46 minutes to win his second-round match, Wawrinka didn't even need to lift a racket after Spaniard Nicolas Almagro pulled out because of pain in his left foot.